Sound identification systems

A method of controlling a camera system, the camera system including at least one camera, at least one microphone to capture sound, and a digital sound recognition system to recognise one or more target sounds in said captured sound, the method comprising:

• inputting sound data for a sound, the sound data defining frequency domain data, said frequency domain data defining an energy of said sound in a plurality of frequency ranges;
• receiving and storing in non-volatile memory pre-derived statistical model parameters representing a set of statistical models λ representing a set of said target sounds, wherein said parameters characterise said set of target sounds;
• performing a multiple component decomposition of said sound data by applying a succession of windows to said sound data to construct a time frequency representation of said sound data;
• calculating, for said set of statistical models λ representing said set of said target sounds, the probability of an observed frequency distribution sequence in said multiple component decomposition of said sound data up to a time T, given the model λ:
• P
• ⁡
• (
• O
• ❘
• λ
• )
• =
• ∑
• i
• =
• 1
• N
• ⁢
• ⁢
• α
• T
• ⁡
• (
• i
• )
• where αt(i) represents the probability of observing said time frequency representation of said sound data up to time t, where i indexes a state of said model defined by mean and covariance values, and wherein P(O|λ) characterises how a frequency distribution of said statistical model λ changes over time;
• applying a set of threshold values to said probability of an observed frequency distribution sequence in said multiple component decomposition to classify said sound data according to said set of statistical models λ;
• and
• moving a view of said camera in response to classification of said sound data according to said set of statistical models λ to direct said camera towards a recognised target sound.

A non-transitory data carrier carrying processor control code for controlling a camera system, the camera system including at least one camera, at least one microphone to capture sound, and a digital sound recognition system to recognise one or more target sounds in said captured sound, wherein the processor control code comprises code to:

• input sound data for a sound, the sound data defining frequency domain data, said frequency domain data defining an energy of said sound in a plurality of frequency ranges;
• receive and store in non-volatile memory pre-derived statistical model parameters representing a set of statistical models λ representing a set of said target sounds, wherein said parameters characterise said set of target sounds;
• perform a multiple component decomposition of said sound data by applying a succession of windows to said sound data to construct a time frequency representation of said sound data;
• calculate, for said set of statistical models λ representing said set of said target sounds, the probability of an observed frequency distribution sequence in said multiple component decomposition of said sound data up to a time T, given the model λ:
• P
• ⁡
• (
• O
• ❘
• λ
• )
• =
• ∑
• i
• =
• 1
• N
• ⁢
• ⁢
• α
• T
• ⁡
• (
• i
• )
• where αt(i) represents the probability of observing said time frequency representation of said sound data up to time t, where i indexes a state of said model defined by mean and covariance values, and wherein P(O|λ) characterises how a frequency distribution of said statistical model λ changes over time;
• apply a set of threshold values to said probability of an observed frequency distribution sequence in said multiple component decomposition to classify said sound data according to said set of statistical models λ;
• and
• move a view of said camera in response to classification of said sound data according to said set of statistical models λ to direct said camera towards a recognised target sound.